Vacuum flask



FIG. 1 is a perspective view of vacuum flask showing my new design;

FIG. 2 is a front view thereof; opposite rear view being mirror image thereof;

FIG. 3 is a left view thereof;

FIG. 4 is a right view thereof;

FIG. 5 is a top view thereof;

FIG. 6 is a bottom view thereof; and,

FIG. 7 is an exploded perspective view thereof. 

CLAIM The ornamental design for a vacuum flask, as shown and described. 